Atomic energy power plants usually comprise a reactor with a fuel cell and a plurality of downcomers that extend from the reactor in downward directions into a torus-shaped chamber positioned below and about the reactor. The torus-shaped chamber is partially filled with deionized water, and the lower open ends of the downcomers are submerged in the water. If the reactor should overheat, steam from the reactor will move through the downcomers and into the deionized water in the torus-shaped chamber.
The typical torus-shaped chamber used in connection with an atomic reactor is oriented in a horizontal attitude and is a substantially closed chamber, in that only small manhole openings are located in a few positions about the upper portion of the chamber. The typical chamber size has an inside height of 30 feet with an overall diameter of about 90 feet. The approximately torus-shaped chamber is formed by 16 cylindrical segments merged end-to-end to form an anulus, with each cylindrical segment forming a bay of the chamber. The deionized water fills the lower one-half portion of the torus, and various catwalks, scaffolds and ductwork are mounted throughout the chamber so as to provide access for the workers within the chamber and to provide ventilation, etc.
It is necessary to refurbish the reactor, including the torus-shaped chamber, from time to time. When refurbishing the chamber, the water is removed from the chamber, and the refurbishing process usually comprises sandblasting the inside surfaces of the chamber, particularly the surfaces normally below the water line, applying several coats of paint to the surfaces, and then drying or curing the painted surfaces.
When the atomic reactor is shut down, it is estimated that the value of the electrical current not generated during shutdown is $750,000.00 per day. Thus, it is important that the refurbishing process should be achieved rapidly.
In the past, a multiple number of workers have been used simultaneously to achieve the refurbishing process. The step of sandblasting was accomplished on a mass basis, and after the sandblasting had been achieved and the sand removed from the chamber, the painting began. Usually the paint was applied in three coats, with each coat requiring twenty-four hours drying time with heated air at less than 65% percent humidity circulated through the chamber. The drying procedure included moving air from outside the chamber through the chamber and heating the air as it entered the chamber to increase the drying effect of the air. In addition, after all three coats of paint were applied to the inner surfaces of the torus-shaped chamber, it was necessary to cure the paint for a prolonged period. Of course, the increased temperature of the drying air and the fumes in the air made it so uncomfortable for workers within the chamber that other work would stop as the chamber was being dried.